package com.test;

import java.util.HashSet;
import java.util.Set;

public class HashSetDemo {

    public static void main(String[] args) {

        Set<Student> students = new HashSet<>();
        students.add(new Student("张三", 10));
        students.add(new Student("李四", 12));
        //添加name和age相同的Student对象
        students.add(new Student("张三", 10));

        for (Student student : students) {
            System.out.println("hashcode:" + student.hashCode() + "," + student);
        }
    }
}

class Student {

    private String name;

    private int age;

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Student student = (Student) o;

        if (age != student.age) return false;
        return name != null ? name.equals(student.name) : student.name == null;
    }

    @Override
    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + age;
        return result;
    }
}

